The present study aimed to analyze the developmental trajectories of English achievement and exposure time through private education, utilizing univariate and multivariate latent growth curve analysis. This study used a subset of the Gyeonggi Education Panel Study data from 2012 to 2017. The results indicated consistent disparities in the growth of English achievement, depending on the student’s proficiency levels at the starting point. In particular, the early exposure to private tutoring was significantly and closely related to the initial status and the growth trajectory of English achievement. When the sample was classified by urbanicity, the findings suggested that the gap in English achievement was likely to increase over time across the two regions, with a stronger correlation with private tutoring found in urban areas. These results underscore the need for educational intervention for students in less advantageous conditions, and they provide valuable pedagogical implications for teaching English in the Korean EFL context.

Background: Sperm quality and the number of sperm introduced into the uterus during artificial insemination (AI) are pivotal factors influencing pregnancy outcomes. However, there have been no reports on the relationship between sperm concentration at AI and sperm quality in Hanwoo cattle. In this study, we examined sperm quality and pregnancy rates after AI using sperm inseminated at different concentrations. Methods: We evaluated the motility, viability, and acrosomal membrane integrity of sperm at different concentrations (10, 15, 18, and 20 million sperm/straw) in 0.5-mL straws. Subsequently, we compared the pregnancy rates after AI with different sperm concentrations. Results: After freeze-thawing, sperm at the assessed concentrations showed similar viability and acrosomal membrane integrity. After AI, cattle in the 10 million group had significantly lower pregnancy rates compared to those in the 18 and 20 million groups. Conversely, there were no statistically significant variances observed between cattle in the 10 and 15 million groups. Conclusions: Sperm at concentrations of 10, 15, 18 and 20 million per straw exhibited comparable motility, viability, and acrosomal membrane integrity. However, a concentration of at least 18 million sperm per straw is required to achieve a consistent rate of pregnancy rate in Hanwoo cattle after AI.

This study evaluated the risk of single and combined exposure to microplastics in zebrafish (Danio rerio) through biomarkers, such as survival rate, excretion rate, and histological alterations of organ systems. The experimental groups were the control (Cont.), single microplastics exposure group (MPs, 1.83%/fish total weight (g)), the copper group (Cu, 21.6 μg L-1), and a group with combined exposure to MPs and copper (MPs*Cu). The experiment was conducted with individual exposure (7 days) for MP excretion rate analysis and group exposure (14 days) for biomarker analysis. The daily excretion rate of MPs tended to decrease in a time-dependent manner. The copper concentration in the body was not significantly different between single and combined copper exposure. The degeneration of mucous cells in the skin, capillary dilation of the gill lamella, increased intestinal mucous, hepatocyte hypertrophy, and the degeneration of glomeruli and renal tubules were observed in all exposure groups. These histological alterations showed the highest tendency in the MPs*Cu group. In this study, the changes in biomarkers were attributed to the single effect of copper or the combined effect of copper and MPs rather than being solely influenced by MPs.

Aligned with the recent shift in fruit consumption trends, there is a growing increase in the cultivation of these fruits. Thus, various types of small fruits, including blueberries, have recently been introduced and cultivated in Korea. According to the data, there has been a notable uptick in blueberry farming, in stark contrast to the decline in cultivation of black raspberries, black chokeberries, and blackcurrants. New varieties of blueberries continue to be introduced and cultivated, aligning with the recent consumption trends and are expected to be consistently cultivated in the future. Despite the decrease in the other berries, health benefits associated with all berries have ignited growing consumer interest, resulting in domestic and international market expansion. In conclusion, this research underscores the importance of identifying plant varieties that are well-suited to Korea's climatic conditions, validating efficient cultivation strategies, and establishing robust distribution networks to foster sustainable development in the berry industry.

Nasopharyngeal stenosis is defined as a morphological transition of narrowing at the nasopharyngeal region. A 2-yearold, castrated male, Korean short hair cat was referred to the animal medical center, Gyeongsang National University. According to clinical signs, diagnostic imaging, and physical examination, nasopharyngeal stenosis was diagnosed. The staphylectomy was performed using a CO2 laser, and there were not any post-operative complications. The patient was discharged in two days. This report describes the case of nasopharyngeal stenosis in cat and represents that laser ablation could be a good option for surgical management of the nasopharyngeal region with a low complication rate.

This study evaluated the fungicidal efficacy of weakly acidic hypochlorous acid water (WAHW) against Microsporum canis (M. canis) and its therapeutic effect on M. canis-infected mouse skin. WAHW was produced by a WAHW generation module. A fungicidal efficacy test by the broth dilution method was used to determine the lowest effective concentration of the WAHW. The lowest effective concentration of WAHW was less than 10 ppm. For T-1, T-2, and T-3, 30 ppm of WAHW was applied to the infected skin once, twice, and three times a day, respectively, and for T-4, 50 ppm of WAHW was applied once a day. On the 3rd day after the initiation of treatment, skin scores in all of the WAHW-treated groups were significantly decreased compared to those in the positive control group (PC) (p<0.05), and there were no significant differences compared to the normal control (NC). The area of the infected skin in all of the WAHW-treated groups was significantly decreased compared to PC from the first day after the initiation of WAHW treatment (p<0.05). The results showed that WAHW had a fungicidal efficacy on M. canis at less than 10 ppm, and it was effective in improving skin symptoms when 30 ppm of WAHW was applied to the M. canis-infected area once a day for five days or 50 ppm of WAHW was applied once a day.

The inorganic scintillator used in gamma spectroscopy must have good efficiency in converting the kinetic energy of charged particles into light as well as high light output and high light detection efficiency. Accordingly, various studies have been conducted to enhance the net-efficiency. One way to improve the light yield has been studied by coating scintillators with various nanoparticles, so that the scintillation light can undergo resonance on surface between scintillators and nanoparticles resulting in higher light yield. In this study, an inorganic scintillator coated with CsPbBr3 perovskite nanocrystals using dip coating technique was proposed to improve scintillation light yield. The experiment was carried out by measuring scintillation light output, as the result of interaction between inorganic scintillator coated with CsPbBr3 perovskite nanocrystals and gamma-ray emitted from Cs-137 gamma source. The experimental results show that the channel corresponding to 662 keV full energy peak in the Cs-137 spectrum shifted to the right by 14.37%. Further study will be conducted to investigate the detailed relationships between the scintillation light yield and the characteristics of coated perovskite nanoparticles, such as diameter of nanoparticles, coated area ratio and width of coated region.

Radioactive waste is typically disposed of using standard 200 and 320 L drums based on acceptance criteria. However, there have been no cases evaluating the disposal and suitability of 200 L steel drums for RI waste disposal. There has been a lack of prior assessments regarding the disposal and suitability of 200 L steel drums for the disposal of RI waste. Radioactive waste is transported to disposal facilities after disposal in containers, where the drums are loaded and temporarily stored. Subsequently, after repackaging the disposal drums, the repackaged drums are transported to disposal facilities by vehicle or ship for permanent disposal. Disposal containers can be susceptible to damage due to impacts during transportation, handling, and loading, leading to potential damage to the radiation primer coating during loading. Additionally, disposal containers may be subject to damage from electrochemical corrosion, necessitating the enhancement of corrosion resistance. Metal composite coatings can be employed to enhance both abrasion resistance and corrosion resistance. The application of metal composite coatings to disposal containers can improve the durability and radiation shielding performance of radioactive waste disposal containers. The thickness of radioactive waste disposal containers is determined through radioactive shielding analysis during the design process. The designed disposal containers undergo structural analysis, considering loading conditions based on the disposal environment. This paper focuses on evaluating the structural improvements achieved through the implementation of metal composite coatings with the goal of enhancing corrosion and abrasion resistance.

The operation time of a disposal repository is generally more than one hundred years except for the institutional control phase. The structural integrity of a repository can be regarded as one of the most important research issues from the perspective of a long-term performance assessment, which is closely related to the public acceptance with regard to the nuclear safety. The objective of this study is to suggest the methodology for quantitative evaluation of structural integrity in a nuclear waste repository based on the adaptive artificial intelligence (AI), fractal theory, and acoustic emission (AE) monitoring. Here, adaptive AI means that the advanced AI model trained additionally based on the expert’s decision, engineering & field scale tests, numerical studies etc. in addition to the lab. test. In the process of a methodology development, AE source location, wave attenuation, the maximum AE energy and crack type classification were subsequently studied from the various lab. tests and Mazars damage model. The developed methodology for structural integrity was also applied to engineering scale concrete block (1.3 m × 1.3 m × 1.3 m) by artificial crack generation using a plate jacking method (up to 30 MPa) in KURT (KAERI Underground Research Tunnel). The concrete recipe used in engineering scale test was same as that of Gyeongju low & intermediate level waste repository. From this study, the reliability for AE crack source location, crack type classification, and damage assessment increased and all the processes for the technology development were verified from the Korea Testing Laboratory (KTL) in 2022.

This study investigated the effectiveness of various chlorinating agents in partitioning light water reactor spent fuel, with the aim of optimizing the chlorination process. Through thermodynamic equilibrium calculations, the effects of using MgCl2, NH4Cl, and Cl2 as a single chlorinating agent or applying MgCl2, NH4Cl, and Cl2 sequentially for spent fuel chlorination were evaluated Furthermore, in this study, assuming the actual process operation situation, where only a part of the semi-volatile nuclides is removed during the heat treatment process, and including the process of precipitating the molten salt from the chlorination process with K3PO4 and K2CO3 precipitants, the percentage distribution of 50 nuclides in the light water reactor spent fuel into each process stream was quantitatively calculated using the simulation function of the HSC program and tabulated for intuitive viewing. Compared to a single chlorinator, sequential chlorination more effectively separated the heat and radioactivity of the spent fuel from the uranium-dominated product solids. Specifically, the sequential application of the chlorinating agents following heat treatment led to a final solid separation characterized by 93.1% mass retention, 5.1% radioactivity, and 15.4% decay heat, relative to the original spent fuel. The findings underscore that sequential chlorination can be an effective method for spent fuel partitioning, either as a standalone approach or in combination with other partitioning processes such as pyroprocessing.

Korea has an agreement for cooperation with 31 countries, including the United States, Canada, Australia, and Japan. Under the agreement, the obligated items must be used for peaceful purposes, comply with nuclear non-proliferation and international safeguards, and obtain prior consent of shipment in case of enrichment, reprocessing, retransfer. Among them, the United States, Canada, and Australia have signed Administrative Arrangements of Cooperation Agreements (Supplementary Arrangements in Canada) for the international transfer and annual reports of obligated items. When operators submit an annual report, the government compiles and make the annual report based on the data. Ideally, the final report is submitted by the operator should be the national annual report, but in practice, discrepancies occur between sum of the operator’s and goverment’s. In order to resolve these problems and strengthen the linkage between exports contrpol and safeguards, our institute has begun the project to develop an ‘Obligation Tracking System for internationally controlled items (OTS)’. It is believed that obligated items which are unnecessarily included or omitted in annual report could be managed properly by developing OTS for life cycle of the items such as import, disposal/ termination or transfer to other countries. In case of nuclear material, especially, the characteristics of the facilities (e.g., bulk-handling facilities) must be considered and principles of fungibility, equivalence, and proportionality should be applied to materials. In order to computerize these procedures, we would like to propose to adopt the format of Code 10 for obligated item management. Code 10 is the form of the annex to the Korea-IAEA safeguards agreement which includes all records of inventory changes, import/export, and domestic movement of nuclear materials. It is expected to minimize discrepancies between operators’ annual reporting data and national annual reporting and further contribute to enhancing national trust and nuclear transparency.